The Potato Sack sale kicked off over the weekend on Steam. The sale knocks 50% off 13 indie games, including Super Meat Boy, Amnesia: The Dark Descent, Killing Floor and more. The whole bundle is 75% off, and you'll get a potato hat in Team Fortress 2.

This isn't just an ordinary sale, thought. There's something weird and potato related happening. Several games in the potato pack have received some unusual updates. Egyptian hieroglyphics have been found in Amnesia, potato references have been found in Defence Grid: The Awakening, and plugging a Razer peripheral in to Kick It! will trigger one of fifteen potato related phrases like this one "never trust a potato...they have eyes everywhere. They are always listening...we never went to space! SPUDnik was a Russet Conspiracy!" What the spud is going on?

VG247 note that a wiki has been set up to collect the mounting clues, though nobody has any idea where any of it is leading. Valve revealed Portal 2 through a series of encoded images and radio messages patched into Portal 1. Could there be another reveal on the cards, or is it all an elaborate, long running April fools hoax?

Here's a list of the games that are part of the potato sack sale. Head over to Steam to take advantage of the deals. There's no end date for the sale yet.

We just released two new bonus levels, totally free! Furthermore, we removed situations in with both blue and purple cubes appeared within the same level, to avoid problems with colorblind people (such as myself ;))

The year 2010 has been great for Two Tribes: bringing Toki Tori and our new game RUSH to Steam and publishing indie classic Frenzic on DSiWare.

We’ve got a number of great games lined up for next year: *project unknown* (iPhone), EDGE (Steam), Swords & Soldiers (iPhone/iPad), Toki Tori (iPad, Mac App Store)! Feel free to check out the attached Christmas card to see if you can discover any hidden secrets :)

We are looking forward to another great year and hereby wish you a merry Christmas and a happy new year on behalve of all the natives at Two Tribes!